Serum copper and related variables in rheumatoid arthritis.

Serum copper, caeruloplasmin, iron, iron-binding capacity, and antioxidant activity were measured in 120 normal subjects and in 189 patients with rheumatoid arthritis. Both serum copper and serum caeruloplasmin were significantly raised in rheumatoid disease in both sexes. A significant inverse relation was found between serum iron and serum copper, and a strong direct correlation between serum antioxidant activity and caeruloplasmin.